Articles written in Sadhana

    • Numerical investigation of single bubble dynamics in liquid sodium pool


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      The single gas bubble rise dynamics in liquid sodium/sodium-potassium alloy (NaK) pool due to entrainment of argon cover gas/non-condensable fission gas (xenon) have received considerable attention in the safe operation of Sodium-cooled Fast Reactor (SFR). Numerical simulation of single bubble dynamics in liquid sodium/NaK pool is an essential intermediate step for the evaluation of rise velocity and shape changes, which are of utmost importance in areas of reactor safety concerned with source term evaluation and cover gas purification. The interFoam solver of OpenFOAM package is used to evaluate inert gas bubble rise dynamics in stagnant liquid metal pool of sodium and NaK. The governing equations are discretized and solved using the Volume of Fluid (VOF) based solver available in OpenFOAM with appropriate initial and boundary conditions.The VOF module of the solver is validated against numerical benchmark data and experimental results available in literature. The bubble dynamics in liquid sodium/NaK pool are studied in terms of trajectory, shape and risevelocity for diameters ranging from 10 to 20 mm, domain aspect ratios and for different gas-liquid systems. The study shows that the bubble rise velocity increases with diameter for liquid sodium systems. The rise behavior ofsingle inert gas bubble in liquid water and sodium pool are compared. The study supports the use of air-water system as a simulant for studying bubble dynamics in liquid sodium systems as suggested by other researchers. The study is very useful and forms an intermediate step towards the development of an OpenFOAM basedcomputational framework to analyze heat and mass transfer from single bubble rising in liquid sodium pool for reactor safety studies.

    • Investigations on the interaction of surface radiation and turbulent natural convection in enclosures with multiple positions of source and sink


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      A numerical investigation is performed for heat transfer phenomena occurring in enclosures with different aspect ratios, emissivities and Rayleigh numbers. Interaction of surface radiation and turbulent natural convection of differentially heated enclosures with different positions of heat source and sink has been assessed systematically. The mass, momentum and energy equations have been solved in two-dimensional cartesian coordinates. The turbulence has been modeled using k - ε model. The simulations have been performed on rectangular enclosures with different aspect ratios (0.5, 1, 1.5 and 2) filled with air having Prandtl number 0.7. Surface to Surface radiation model has been incorporated to study the effect of surface radiation on the heat transfer characteristics. The results have been presented in terms of Nusselt number, isotherms and streamlines for various cases. It is concluded that the results can provide insight when designing enclosures for complex engineering applications involving turbulent conditions.

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